Ultra high frequency discharge tubes



Sept. 27, 1960 Filed Jan. 3, 1956 G. MOURIER ULTRA HIGH FREQUENCY DISCHARGE TUBES {IIIIIII 3 Sheets-Sheet 1 Sept. 27, 1960 G. MOURIER ULTRA HIGH FREQUENCY DISCHARGE TUBES 3 Sheets-Sheet 2 Filed Jan. 3, 1956 Q S m Sept. 27, 1960 G. MOURIER 2,954,505

ULTRA HIGH FREQUENCY DISCHARGE TUBES Filed Jan. 3, 1956 5 Sheets-Sheet 5 l l l l l'l' ULTRA HIGH FREQUENCY DISCHARGE TUBES Georges Mourier, Paris, France, assignor to Compagnie Generale de Telegraphic Sans Fil, a corporation of France Filed Jan. 3, 1956, Ser. No. 557,099 Claims priority, application France Jan. 11, 1955 18 Claims. (Cl. SIS-39.3)

Numerous types of ultra high frequency tubes are known which comprise a delay wave guiding structure along which an electron beam is propagated in interaction with energy propagating in this structure. In all these tubes, the wave propagation taking place in the direction of the beam, is the only one which is made use of.

The tube according to the invention comprises a delay line structure adapted to ensure energy propagation along two mutually intersecting directions. In one direction the ends of the delay structure are mutually coupled. Therefore, when energy is propagated in the delay structure, for amplification or by generation within the tube, standing waves appear in this direction.

The energy to be amplified is fed for propagation along thesecond direction while one. or a plurality of electron beams are propagated along the first direction for interaction with the standing waves.

For making the tube oscillate, some kind of feed-back coupling, such as, for example, a conventional external feed-back must be provided between input and output of the structure in the second direction.

The invention will be better understood from the ensuing specification and the appended drawing, wherein:

Fig. 1 diagrammatically shows a first embodiment of the tube according to the invention;

Fig. 2 is a perspective view of a further embodiment of the tube according to the invention;

Fig. 3 is a longitudinal section of a detail of Fig. 2;

Fig. 4 shows another embodiment of the tube according to the invention, in the same diagrammatic way as inFig. 1.

Figure 1 very diagrammatically shows a tube according to the invention, moreparticularly adapted to be usedas an amplifier. This tube comprises, within an evacuated envelopeE, a rectangular delay structure 1, adapted for propagating ultra high frequency waves, both in the OX and in the; OY directions. More particularly, this structure may be considered as built up from a plurality of delay lines, or channels, N and M, arrangedin parallel relationship along the OX and OY directions, respectively, each channel being coupled to the adjacent channels.

In this embodiment'of the tube according to the invention, the delay structure 1 has its ends, or edges, AB and CD mutually coupled and its ends, or edges, AC and BDmutually uncoupled. Thismay, for instance, be performed by the provision of reflecting planes R and R, arranged along sides AB and CD of the delay structure normally to the plane of the drawing. A cathode 2 projects a laminar electron beam, or a plurality of parallel beams, 3-.in the OY direction. Any suitable focalisation system may be used to focalise the beam. The electrons follow paths parallel to-delay channels M and are collected by a collector4. The ultra high frequency energy to be amplified is fed, by any known means, into side AC of the delay structure 1 in such a manner that a travelling wave is excited in the direction OX, with a phase varying by a constant amount. from channel N to the next. The amplified energy is abstracted from the opposite side BD in such a manner that travelling waves in all the channels N are collected in a common output in proper phase relationship.

An energy source 9 brings delay structure 1 and collector 4 to a common positive potential and cathode 2 to a negative potential. The resulting potential difference, which can be readily adjusted, defines the velocity of electron beam 3.

It will be noted that a number of examples. of bidimensional delay lines have been disclosed in a patent application by P. Palluel, Serial No. 557,022, filed on the same date as the present application and assigned to the same assignee and now Patent No. 2,888,598.

While it is to be understood that the applicant does not intend to be limited to, or bound by, any kind of explanation, since the invention refers essentially to a novel tube structure and to the use thereof, it is believed that the operation of this tube, as an amplifier, may be broadly explained as follows The energy to be amplified, which is applied along the OX direction, is propagated in this direction in the same way as it is propagated in. con? ventional traveling. wave tubes, i.e. in traveling waves Further, experience and theory show that, as soonuasi energy propagates in the direction OX, standing Waves appear in the OY direction on account. of the reflecting planes arranged along the edges AB and CD respectively or, broadly speaking, because of the coupling existing be tween these edges -of delay structure 1. Thus, in eachchannel M there exists acertain amount of standing waves, propagating according to various discrete modes, the phase-shift y, between two adjoining cells being such. that the sum of the phase-shifts of each channel M is equal to K.1r, K being an integer, since the waves considered are standing waves.

As is well known, a standing wave may be decomposed into two traveling waves propagating in opposite directions. Therefore, the velocity of, beam 3 is substantially synchronized with one of the space harmonics building up the traveling waves; interaction takes place between the beam andthe wave just as in any conventional traveling wave tube. Theory and experience show that energy induced by the beam at any point of the structure propagates in the same direction as the energy fed to the delay structure and, under these conditions, ultra high frequency energy propagated from input 5 to output '7 is amplified.

Preferably, beam 3 will be caused to interact with a traveling wave component of the standing wave for which the phase-shift i is equal to 1r.

Accordingly, the delay structure 1 is conveniently provided with a strapping similar to a magnetron strapping. Assuming the tube in Figure l to be adapted to operate according to mode 1r, alternate cells in the direction OY are connected by strappings 6a and 612 along the side AC, and 8a and 8b along the side BD. In this case, bifilar lines 20 and 21" are provided at the input and the output, respectively, for feeding the input energy to two strappings 6a and 6b, in phase opposition and for collecting the output energy. I

Figure 2 is a perspective view, partially broken away, of a particular embodiment of the tube according to the invention. According to this embodiment, the delay structure corresponding to structure 1 of Figure 1, has been rolled upto form a cylinder, so that the edges AB and CD are coupled by physical contact rather than by. provision of reflecting planes. The result is of course the same i.e. standing waves appear in the OY direction, this direction being, in this case, tangential or circumferential, while the OX direction is axial. The tubeis located in an axial magnetic field which bends the electron beam OY direction.

The tube of Figure .2 comprises a metal envelope 10 containing a bi-dimensional delay structure formed by plates, or irises, 11, uniformly spaced in the axial direction OX. Vanes 17 are cut out in plates 11. They are uniformly spaced to form a delay line in the OY direction. Each plate 11 is provided with a central perforation communicating with slots 18 defining vanes 17. An axial cathode 12 extends throughout the whole tube. It is carried at its ends by insulating flanges 13 and 14 and is heated by means of a filament 15. The axial magnetic field is produced by a coil 16. The tube is provided with an input and an output 7. Straps 6 and 8 are also provided.

In operation, traveling waves propagate along the OX direction and standing waves are present in the OY direction, just as in the case of Fig. 1.

The amplifier according to the invention is not directional, i.e. it is capable of amplifying the energy propagated either from left to right or from right to left. Stray oscillations are thus liable to occur and to avoid this inconvenience, gain must be limited. In order to escape this drawback and to make the tube directional, directive attenuating means are located on one side of the delay system. A ferrite block may, for instance, be used. It is known that ferrite, when immersed in a magnetic field, displays directional conductivity and, therefore, is directionally attenuating. This attenuating sub stance may be disposed on the few first, or the few last, irises of Fig. 2, as shown at 19 in Fig. 3.

The amplifiers according to the invention have the important advantage of providing a high gain per unity of length, through a wide frequency band. It may be shown that, in the tube above described, the gain is inversely proportional to the group velocity of the propagated wave and that it is possible to maintain the latter at a low value.

The tube shown in Fig. 2 has the same efficiency as the magnetron and has a high output power, on account of the energy which may be accumulated along the tube.

Comparatively high output can always be obtained Owing to the possibility of making use of beams of large cross-section.

In another embodiment of the invention reflecting planes Ra and Ra may be provided along the edges AC and BD, in addition to reflecting planes R and R shown inFig. 1.

In this case, the tube will be more particularly used as an oscillator.

Such a tube is shown in Fig. 4. As may be easily seen, the structure is exactly the same as in Fig. 1 except for the fact that there is no input and that planes Ra and Ra have been provided. In this case, the ultra high frequency energy propogates in standing waves in both directions. This energy is coupled in the direction OX to the output 25, for instance by providing an aperture in the reflecting plane Ra.

The oscillating energy is built up in the usual way along the direction OY, the regeneration taking place by reflection along the channels M. Since channels N are coupled to channels M, standing waves also appear between planes Ra and Ra.

A strapping similar to the strapping of Fig. 1 can be provided. 7

The advantages are the same as in the case of an amplifier.

What is claimed is:

1. An ultra high frequency discharge tube comprising: .a delay structure which is geometrically periodical in two :mutually intersecting directions; an electron source positioned for propagating electrons along said structure in a first one of said two directions; input and output means defining therebetween a path for travelling waves in the second of said two directions said input means compri sv so to cause it to follow a circular path in the 4 ing means for feeding travelling waves to said structure with a phase varying periodically in the space along said first direction; and means for establishing in said structure standing energy waves in said first direction.

2. A tube according to claim 1, further comprising a unidirectional attenuator positioned for attenuating said traveling waves. V

3. A tube according to claim 1, further comprising a ferrite attenuator located in the path of said traveling waves, and means for subjecting'said ferrite'attenuator to amagnetic field. e p

4. An ultra high frequency discharge tube comprising: a delay structure which is geometrically periodical in two directions perpendicular to each other and having a first and a second pair of opposed edges; input means positioned along one edge of the first pair for feeding energy to said structure; output means positioned along an edge opposed to said first edge for abstracting traveling wave energy propagating in one of said two directions; an electron source extending along one of the edges of said second pair of edges for emitting at least one electron beam along said structure in the other of said directions; and reflecting means respectively positioned along the edges of said second pair.

5. An ultra high frequency discharge tube comprising: a delay structure having a plurality of uniformly spaced parallel plates, each plate having acentral perforation and cutaway portions extending from'said central perforation and uniformly spaced around the latter; an elongated cathode extending through said central perforations essentially normally to said plates; means for providing a magnetic field essentially normal to said plates; input means adjacent one endof said cathode for propagating energy along said delay structure and output means for collecting said energy adjacent the other end of said cathode.

6. An ultra high frequency discharge tube comprising:

a delay structure having a' plurality of uniformly spaced parallel plates, including two end plates, each plate hav-' ing a central perforation and cutaway portions extending from said central perforation and uniformly spaced around the latter; an elongated cathode extending through .said central perforations essentially normally to' said plates; means for feeding ultra high frequency energy to one of said end plates and means for collecting energy from the other end plate.

7. A tube according to claim '6, further comprisinga ferrite attenuator at one of the ends of said delay struc-iture.

8. An ultra high frequency discharge tube comprising: a delay structure which is geometrically periodical in two mutually intersecting directions, said structure having its ends mutually coupled in a first one of said two directions and uncoupled in the second direction; input means at one of said uncoupled ends for feedingenergy to said structure with a phase varying periodically in the space from one of said coupled ends to the other; means for propagating electrons in said first direction in coupled. relationship with said line for interaction with energy existing along said first direction; and energy output means at said other uncoupled end. H

9. An ultra high frequency discharge tube comprising: a delay structure which is geometrically periodical in two directions perpendicular to each other and havinga first and a second pair of opposed edges; output means positioned along one edge of said first pair for abstracting traveling wave energy propagating in one of said two directions; an electron source extending along one of the edges of said second pair of edges for emitting at least two diiferent directions forming an angle therebetween,

means including an electron source for propagating electrons along said structure with velocity components thereof in at least one of said two directions, input and output means defining therebetween a path for travelling waves in one of said two directions, said input means including feed means for feeding energy to said structure with a phase varying periodically in the space along the other direction, and means for establishing in said structure standing wave energy in said other direction.

11. A traveling wave tube comprising a wave propagating structure adapted to propagate therealong traveling signal waves in two different directions, means for propagating at least one beam of electrons in paths along said structure in wave interaction relationship therewith in such a manner as to produce amplification of the traveling waves in one of said two directions by interaction of the electron beam with the traveling waves in the other of said two directions, and means for removing the amplified wave traveling in said other direction.

12. A traveling wave tube comprising a multi-dimens-ional delay structure adapted to propagate therealong traveling signal waves in two diflerent directions, and means for propagating electrons in paths along said structure with velocity components in one of said two directions to provide energy interaction between the traveling waves and said electrons in said one direction While simultaneously therewith amplifying the traveling waves in the other of said two directions.

13. A traveling wave tube comprising a wave propagating structure adapted to propagate therealong traveling signal waves with predetermined phase velocities in two difierent directions, means for producing at least a traveling wave in one of said two directions, and means for projecting a beam of electrons in paths along said structure with velocity components in said one direction to provide interaction between the electrons of said beam and said traveling wave in said one direction to thereby produce amplification of a traveling wave in said other direction.

14. A traveling wave tube according to claim 13, wherein said two directions are essentially mutually perpendicular.

15. A traveling wave tube according to claim 14, wherein one of said directions is axial and the other is circumferential.

16. A traveling wave tube comprising an elongated delay structure adapted to propagate therealong traveling waves in two directions at predetermined phase velocities in said two directions, and means for propagating electrons in paths along said delay structure in interaction with the traveling waves in at least one of said two directions while producing amplification of the traveling waves in the other direction.

17. An ultrahigh-frequency discharge tube comprising delay means which is geometrically periodical in two directions, output means operatively connected with said delay means 'for abstracting traveling wave energy propagating in one of said two directions, a source of electrons, and means for propagating the electrons from said source in energy transfer relationship with said delay means with the electrons thereof having velocity components in the other of said two directions to thereby produce amplification of the traveling waves in said one direction by interaction in said other direction.

18. An ultra-'high-frequency discharge tube according to claim 17, further comprising means operatively connected with said delay means to generate oscillatory energy within said tube.

References Cited in the file of this patent UNITED STATES PATENTS 2,439,401 Smith Apr. 13, 1948 2,640,951 Kuper June 2, 1953 2,651,686 Clavier et a1. Sept. 8, 1953 2,806,972 Sensiper Sept. 17, 1957 2,858,472 Karp Oct. 28, 1958 

